1. Field of the Invention
The present invention relates to charge pumps and liquid crystal displays (LCDs) having charge pumps.
2. Description of the Related Art
FIG. 1 depicts a liquid crystal display (LCD) 100 which comprises a display area 102 and an LCD driver 104. The LCD driver 104 typically receives a reference voltage VCI from an exterior source to generate positive and negative voltages (hereinafter VSP and VSN) for driving the display area 102. Generally, a charge pump is required in the LCD driver 104 to generate the voltage VSP and VSN.
However, conventional charge pumps usually have poor application flexibility. The generated voltages VSP and VSN are limited by the structure of the charge pump. The circuit of the charge pump has to be redesigned when target values of the voltages VSP and VSN are changed.
Furthermore, the generated voltages VSP and VSN may deviate from their target value because of the load current.
Also, in some cases, the charge pump may cause considerable peak current in its charge or pump periods. The undesired peak current increases power consumption and hinders LCD application in portable consumer electronic products.
To solve at least the aforementioned drawbacks, novel charge pump techniques are called for.